The comments from the most senior judge in England and Wales came after a panel of legal experts said the current law treated mercy killers on the same basis as serial killers.

The dedicated and beatific Dr. Cook was no mere mercy killer who made house calls.

"I'd still guess it's some misguided mercy killer," David said.

Doctors would soon become mercy killers.

"He's here to see what the mercy killer is really like," he said.

He was a mercy killer.

"He's no mercy killer, and he's not insane," said Mr. Ney, speaking to a courtroom packed with families of the victims.

The difficulty with the counter-arguments is that the practice of 'stretching' diminished responsibility gives a de facto defence to mercy killers already.

Even people who disapproved of euthanasia, these lawyers said, could say that it would be irrational to impose on a mercy killer the same sentence that would be imposed on cold-blooded killers.